22 AGRICULTURE FOR COMMON SCHOOLS 



The sands have the coarsest particles and the clays the finest, 

 while the loams have fine particles and the most organic mat- 

 ter. Muck soils, being so largely vegetable matter, hold more 

 water than any other kind. Soils that are loose hold more 

 water than compact soils. However, some of the coarser 

 sands hold more water when packed than when loose. When 

 a soil is packed the very finest particles are forced into the 

 smaller capillary spaces and so shut up some of the space that 

 might be occupied by water. This is the case in packed clays 

 and loams. When a coarse soil is packed the smaller parti- 

 cles are forced into those smaller spaces which are too large to 

 hold capillary water, making them smaller and enabling them 

 to hold more moisture than if they were left loose. As an 

 illustration of how much water per cubic foot loose soils will 

 hold we may take the following figures: sandy, 24 pounds; 

 clay, 28 pounds; loam, 32 pounds; muck, 40 pounds. If we 

 take the weight of a cubic foot of water to be 62.4 pounds, 

 then an inch of rainfall will weigh one-twelfth of 62.4 pounds, 

 or 5.2 pounds. Then if the figures above be divided by 5.2 

 we have the following number of inches of rainfall for a cubic 

 foot of each soil: sandy, 4.6, clay, 5.4, loam, 6.1, and muck, 

 7.7. Since all soils vary somewhat the above figures are cor- 

 rect only for the particular soils tested, but they do show how 

 the kinds of soils differ. We must remember that the above 

 figures show what is in the surface foot. The second and third 

 and fourth foot will contain about as much, usually a little 

 less, depending upon the size of the soil particles, so that the 

 total amount of water held in the soil is a great deal. The 

 roots of plants feed mostly in the first two feet. If we could 

 save for use all the water that a soil will hold we should have 

 plenty for all the needs of the crop. However, we have said 



